I am also looking at getting a new Camera this year and have not decided to go FX or stay DX. I am thinking of getting a D750 or D7200 and just weighing up the pros and cons but will probably go FX just have to get some new lens.
I am just putting out there why can a Housing manufacture like Ikelite for example make a housing that can be used for both a D750 and a D7200. The D750 is about the same size as the D7200 some controls are in a different place but the mold would be the same size. They could just make the controls for one camera a different colour then you could use one housing for two cameras either use a DX for Macro and a FX for wide angle would this be to simple?
I understand that a Housing manufacture would think it is losing out selling housings but I would pay a few hundred more for a duel purpose housing and they could offer upgrades on existing D7100 housings as it looks like they will fit the D7200 already.
That would make traveling easer two camera bodies one housing.